Pushchairs

ABSTRACT

A pushchair of the type which includes a chassis which is born upon one or more primary wheels on a primary wheel bearing axis, the chassis further having one or more forward and/or rear secondary wheel(s) or stabilizer(s) that in normal use of the pushchair during horizontal travel is/are not ground engaging but which limit tilting of the pushchair about the primary axis, the pushchair being characterized in that it further includes a selectively operable stabilizer which may be deployed to bring a prop into ground engagement to substantially prevent tilting of the pushchair about the primary wheel axis when the pushchair is stationary.

FIELD OF THE INVENTION

The present invention concerns improvements to pushchairs of the typehaving a chassis which is born upon one or more primary wheels on aprimary wheel bearing axis.

BACKGROUND TO THE INVENTION

The present Applicant's earlier UK Patent GB 2265341 describes a type ofpushchair which has its chassis born upon one or more primary wheels ona primary wheel bearing axis and having forward and/or rear secondarywheels or stabilizers that in normal use of the pushchair are not groundengaging. The chassis and as seat for the child are arranged to placethe center of gravity of the occupied pushchair at or near to theprimary transverse axis, comprising an axle or coaxial series of axles.To which the main wheel or wheels are mounted. The secondary wheels orstabilizers are configured to have ground clearance of severalcentimeters when the pushchair is balanced over the primary axis. Whenthe pushchair is at rest either the front or the rear secondary wheel(s)or stabilizers is/are in ground contact but the other is clear of theground. The function of the secondary wheels or stabilizers is to assistin curb climbing and to provide additional stability, limiting excessivetilting about the primary axis.

The center of gravity of the pushchair is located in this distinctiveway partly in order that the user benefits from the greater mechanicalefficiency of balancing on centralized large main wheel(s) compared withthe spread out relatively small wheels of conventional pushchairs. Theconfiguration also brings substantial advantages when turning. Thebalancing of the weight of the pushchair over the main wheel(s) greatlyfacilitates maneuvering.

Although the design brings significant advantages in use and althoughthe pushchair does have the secondary wheel(s) or stabilizers to limittilting about the primary axis, there is a potential problem of a childmoving about in the seat when the pushchair is stationary causing it torock back and forth about the primary axis. This could be unsettling tothe child and in an extreme case might lead to backward and forwardoscillation that compromises the overall stability of the stationarypushchair.

SUMMARY OF THE INVENTION

According to the present invention there is provided a pushchair of thetype which comprises a chassis which is born upon one or more primarywheels on a primary wheel bearing axis, the chassis further having oneor more forward and/or rear secondary wheel(s) or stabilizer(s) that innormal use of the pushchair during horizontal travel is/are not groundengaging but which limit tilting of the pushchair about the primaryaxis, the pushchair being characterized in that it further comprises aselectively operable stabilizer means which may be deployed to bring aprop means into ground engagement to substantially prevent tilting ofthe pushchair about the primary wheel axis when the pushchair isstationary.

In one preferred embodiment, the forward or rear secondary wheel(s) orstabilizers is/are selectively operable to be deployed to move intoground engagement when the pushchair is stationary.

The stabilizer means may comprise an adjustment mechanism whereby thechassis may be lowered relative to the primary wheel axis to bring theforward or rear secondary wheel(s) or stabilizer(s) into groundengagement.

In such arrangement lowering of the chassis may also bring a brake blockinto contact with the primary wheel(s). This is particularlyadvantageous since it enables operation of the stabilizing mechanism tobe effected simultaneously with braking, greatly simplifying the actionsinvolved in parking of the pushchair.

In an alternative embodiment of the present invention, the selectivelyoperable stabilizer means may comprise an independent prop means that ismounted to the chassis and moveable from a stowed position adjacent thechassis to an extended position in which it props the chassis againsttilting about the primary axis. Such a prop may also be adapted toengage the pushchair primary wheel(s) to simultaneously function as abrake.

Preferably in each of he above embodiments he selective operation of theselectively operable stabilizer means is effected by operation of a handor foot operable lever which is mounted to the chassis of the pushchair.Such lever is preferably pivotally mounted to the chassis of thepushchair.

BRIEF DESCRIPTION OF THE DRAWINGS

Two preferred embodiments of the present invention will now be moreparticularly described, by way of example, with reference to theaccompanying drawings, wherein:

FIG. 1 is a schematic side elevation view of a pushchair of the firstpreferred embodiment while stationary and resting on rear stabilizerwheels;

FIG. 2 is a side elevation view of the pushchair of the first preferredembodiment but with the selectively operable stabilizer means actuatedto bring the chassis of the pushchair down over the primary wheelbearing axis and bring the front stabilizer wheels into ground contact;

FIG. 3 is a schematic side elevation view of a second preferredembodiment of the pushchair stationary and with selectively operablestabilizer means comprising an independent prop, shown in groundengagement; and

FIG. 4 is a side elevation view of the pushchair of the second preferredembodiment and with the prop raised from ground engagement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring firstly to FIGS. 1 and 2, in this first preferred embodimentthe chassis (1) of the pushchair is adapted to be lowered over theprimary wheel axle (2) to fully stabilize the pushchair when stationary.In common with the designs of pushchair illustrated in earlier UK PatentGB 2265341 and PCT/GB93/00595, the wheelchair has one or a pair of mainload bearing wheels mounted on a single primary axle or a pair ofcoaxial axles along a single primary axis (2). The main load bearingwheel(s) (3) is/are substantially larger than the conventional pushchairwheel and may have a diameter of greater than 15 cm, including thethickness of the tire (where present) for example.

The chassis (1) may be of relatively conventional form comprising aframework bearing a seat and with the sides of the framework reachingupwardly to terminate in a handlebar that extends transversely over thepushchair to be gripped by both hands as the pushchair is pushedforward.

In the illustrated embodiment the pushchair has not only the main loadbearing wheels (3) on the primary axis but also one or a pair of frontstabilizer wheels (4) at the front of the pushchair extending forwardlyof the main load bearing wheels (3) and also one or a pair of rearstabilizing wheels (5) extending rearwardly of the main load bearingwheels (3).

Either the front or the rear stabilizing wheels (4, 5) may be in groundengagement at the same time as the main load bearing wheels duringnormal operation of the pushchair. The greatest mechanical advantage ofthe main load bearing wheels (3) is achieved when they alone are inground contact and both front and rear stabilizer wheels (4,5) are clearof the ground. However, for comfort of the user, for example, and duringrest when the pushchair is stationary and not supported by the user, thefront or the rear stabilizing wheels (4, 5) will support the pushchair,as illustrated in FIG. 1.

In this rest position there is only limited opportunity for movement ofthe pushchair tilting about the primary axis (2). However, even thislimited movement may be undesirable. Accordingly, the pushchairincorporates a selectively operable stabilizing means that comprises aseries of pivoted linkages (6, 7, 8) and a hand operating lever (9).When the lever (9) is raised, as illustrated in FIG. 2, this causes thefirst linkage element (6) to pivot rearwardly and upwardly, drawing thesecond linkage element (7) rearwardly and lowering the chassis (1) overthe primary axis/axle (2). As will be appreciated, the first linkageelement (6) is pivotally attached to the chassis (1) at its end engagedwith the lever arm (9). The third linkage element (8) is pivoted aboutthe primary axle (2) and also engages the lower end of the chassis (1).

Lowering of the chassis (1) over the primary axle (2) has the effect ofbringing the front stabilizer wheels (4) into ground engagement. Thiseffectively prevents the pushchair from thereafter tilting about theprimary axle (2) and provides the required stability of the pushchairwhen stationary.

A further effect achieved by lowering of the pushchair chassis (1) isthat it lowers the center of gravity and makes the pushchair inherentlymore stable against destabilizing forces in any direction. An evenfurther effect is that a brake block (10) mounted to the underside ofthe chassis (1) to seat supporting portion (11) is brought into contactwith the main load bearing wheel (3) to brake the pushchair againstforward or rearward rolling motion. This, therefore, providesstabilizing and securing functions with one simple actuating leveroperation.

Turning to the second illustrated embodiment, at FIGS. 3 and 4, thisincorporates a simpler construction of selectively operable stabilizingmeans. Here, the chassis (1) is not adapted to be lowered but insteadthere is an independent prop means (12) pivoted to a lower member (14)of the chassis (1). This prop mean (12) is linked by a wire cable (15)to an operating hand lever (16) on the handle stem/handlebar of thechassis (1). A resilient biasing means/compression spring (17) isprovided to bias the prop (12) to a stowed position, as illustrated inFIG. 4 but is over-ridden by the cable (15) that is pulled by theoperating hand lever (16).

A secondary function of the selectively operable stabilizing means ofthis embodiment is again a braking function. A rear portion (17) of theprop (12) or a member projecting from it serves to engage the main loadbearing wheel (3) to brake the wheel when the prop (12) is brought intoground engagement.

Although not illustrated, a further embodiment of the present inventionmentioned earlier is the provision of a selectively adjustable mechanismfor bringing the front stabilizer wheels (4) (or stabilizer(s)) or therear stabilizer wheels (5) (or stabilizer(s)), whichever is clear of theground when the pushchair is at rest, selectively into ground engagementto prevent the pushchair from tilting about the primary axis (2). Suchmechanism preferably incorporates one or more levers, cables or otherlinkages similarly to the first and second embodiments to enableoperation by the user remotely, Movement of stabilizer wheels (4) or (5)into ground engagement is preferably by pivoting of the stabilizerleg(s) on which the wheels (4) or (5) are mounted.

What is claimed is:
 1. A pushchair of the type which comprises a chassiswhich is born upon one or more primary wheels on a primary wheel bearingaxis, the chassis further having one or more forward and/or secondarywheel(s) or forward and/or rear stabilizers that in normal use of thepushchair during horizontal travel is/are not ground engaging but whichlimit tilting of the pushchair about the primary axis, the pushchairbeing characterized in that it further comprises a selectively operablestabilizer means which may be deployed to bring a prop means into groundengagement to substantially prevent tilting of the pushchair about theprimary wheel axis when the pushchair is stationary, wherein thestabilizer means comprises an adjustment mechanism whereby the chassismay be lowered relative to the primary wheel axis to bring the forwardor rear secondary wheel(s) or stabilizer(s) into ground engagement andlowering of the chassis brings a brake block into contact with theprimary wheel(s).
 2. A pushchair as claimed in claim 1, wherein theforward or rear secondary wheel(s) or forward or rear stabilizer is/areselectively operable to be deployed to move into ground engagement whenthe pushchair is stationary.
 3. A pushchair as claimed in claim 1,wherein the selective operation of the selectively operable stabilizermeans is effected by operation of a hand or foot operable lever which ismounted to the chassis of the pushchair.
 4. A pushchair as claimed inclaim 3, wherein the lever is pivotally mounted to the chassis of thepushchair.
 5. A pushchair as claimed in claim 3, wherein the lever ispivotally mounted to the chassis of the pushchair.
 6. A pushchair of thetype which comprises a chassis which is born upon one or more primarywheels on a primary wheel bearing axis, the chassis further having oneor more forward and/or rear secondary wheel(s) or forward and/or rearstabilizer(s) that in normal use of the pushchair during horizontaltravel is/are not ground engaging but which limit tilting of thepushchair about the primary axis, the pushchair being characterized inthat it further comprises a selectively operable stabilizer means whichmay be deployed to bring a prop means into ground engagement tosubstantially prevent tilting of the pushchair about the primary wheelaxis when the pushchair is stationary, wherein the selectively operablestabilizer means comprises a prop means that is mounted to the chassisand moveable from a stowed position adjacent the chassis to an extendedposition in which it props the chassis against tilting about the primaryaxis, and where the prop is also adapted to engage the pushchair primarywheel(s) to function as a brake.
 7. A pushchair as claimed in claim 6,wherein the selective operation of the selectively operable stabilizermeans is effected by operation of a hand or foot operable lever which ismounted to the chassis of the pushchair.
 8. A pushchair of the typewhich comprises a chassis supported by at least one primary wheelmounted on a primary wheel bearing axle, the chassis further having atleast one stabilizer that in normal use of the pushchair duringhorizontal travel is not ground engaging but which limits tilting of thepushchair about the primary wheel bearing axle, and a brake block, saidpushchair further comprising selectively operable stabilizer meansincluding prop means which may be deployed to bring said prop means intoground engagement to substantially prevent tilting of the pushchairabout the primary wheel bearing axle when the pushchair is stationary,wherein said stabilizer means comprises an adjustment mechanism forlowering the chassis relative to the primary wheel bearing axle to bringsaid stabilizer into ground engagement and wherein lowering of saidchassis brings said brake block into contact with said primary wheel. 9.A pushchair as claimed in claim 8, wherein said chassis has at least twoof said at least one stabilizer, comprising a forward stabilizer and arearward stabilizer.
 10. A pushchair as claimed in claim 9, wherein saidforward and rearward stabilizers each comprising a secondary wheel. 11.A pushchair as claimed in claim 9, wherein said forward and rearwardstabilizers each comprise a pair of secondary wheels.
 12. A pushchair asclaimed in claim 8, wherein the selective operation of the selectivelyoperable stabilizer means is effected by operation of a hand or footoperable lever which is mounted to the chassis of the pushchair.
 13. Apushchair of the type which comprises a chassis supported by at leastone primary wheel mounted on a primary wheel bearing axle, the chassisfurther having at least one stabilizer that in normal use of thepushchair during horizontal travel is not ground engaging but whichlimits tilting of the pushchair about the primary wheel bearing axle,said pushchair further comprising selectively operable stabilizer meansincluding prop means which may be deployed to bring said prop means intoground engagement to substantially prevent tilting of the pushchairabout the primary wheel bearing axle when the pushchair is stationary,said prop means being mounted to said chassis and moveable from a stowedposition adjacent the chassis to an extended position in which it propsthe chassis against tilting about the primary wheel bearing axle, andwhere the prop is also adapted to engage the pushchair primary wheel tofunction as a brake.
 14. A pushchair as claimed in claim 13, whereinsaid chassis has at least two of said at least one stabilizer,comprising a forward stabilizer and a rearward stabilizer.
 15. Apushchair as claimed in claim 14, wherein said forward and rearwardstabilizers each comprising a secondary wheel.
 16. A pushchair asclaimed in claim 14, wherein said forward and rearward stabilizers eachcomprise a pair of secondary wheels.
 17. A pushchair as claimed in claim13, wherein the selective operation of the selectively operablestabilizer means is effected by operation of a hand or foot operablelever which is mounted to the chassis of the pushchair.